1. Field of the Invention
The present invention relates to improvements in or relating to high temperature reactors. More particularly, the present invention is concerned with medium power nuclear reactors in which the primary circuit is enclosed by a prestressed concrete pressure vessel or similar prestressed concrete reactor vessel, and this is supported on foundation walls. A reactor protection building surrounds the prestressed concrete reactor vessel, and is associated with a reactor auxiliary building. The reactor includes a reactor core which is made up of a bed of spherical full elements or pebble bed, which once through the reactor core under the force of gravity, and includes a charging installation for the introduction, as well as means for the withdrawal of operating elements. The pertaining charging conduits, pellet tubes, and exit pipes, as well as functional components for closing, metering, counting, distributing, and collecting of the operating elements are associated with the charging installation. The reactor also includes armored ducts which penetrate the prestressed concrete pressure vessel.
2. Background of the Art
Feed apparatus, or similar charging installations, for nuclear power reactors of medium power in pebble bed reactors are known, such apparatus are designed in accordance with modular design principles, and contain functional components, which can be moved by drives, for the introduction, withdrawal, distribution, and sorting of fuel elements. The functional components exhibit bores for the passage of pellets, and they are set in a block, or a plate, which is respectively provided with connecting bores for the pellets. Such feed apparatus are shown in West German Utility Model No. 6,753,677; West German Auslegeschrift No. 1,589,532; and West German Offenlegungsschrift No. 2,357,426.
The feed apparatus which is described in West German Offenlegungsschrift No. 2,357,426 is used, for example, in the nuclear power plant THTR-300, in which the feed station for the operating elements, fuel pellets and pure graphite pellets, is arranged in an auxiliary building and at a lower elevation than the high temperature reactor (HTR). A central withdrawal duct is provided in this HTR for the removal of the operating elements, and the duct leads to a burn-up measuring apparatus which is arranged in the charging room beneath the prestressed concrete pressure vessel. Because the fuel pellets are passing several times through the reactor core, until they have reached the desired final degree of burn-up, such a measuring apparatus is a necessity. For the same reason, a feed device is installed in the charging room, for conveying those operating elements which can still be used to the reactor core. The device is also used for fresh operating elements. In order to prevent damage of the operating elements due to impinging on the upper surface of the pebble bed or filling, the upper ends of the feed conduits exhibit a delay or deceleration apparatus.
The state of the art further includes German Pat. No. 1,281,046 which also shows a feed apparatus for a so-called pebble bed reactor. The withdrawal and sorting device for the fuel pellets therein is also arranged beneath the reactor core and also exhibits a burn-up measuring apparatus. In accordance with the burn-up readings, the pellets are transferred again into the core, or they are separated from the cycle.